A case study: surface chemistry and surface structure of catalytic aluminas, as studied by vibrational spectroscopy of adsorbed species

Transition phase aluminas have been used as catalysts, and their surface chemical properties have been studied for over 30 years. The various steps of the gradual comprehension of the surface structure and surface chemistry of aluminas are here summarized. Our main attention has been devoted to various aspects of the surface chemistry of aluminas, as revealed by the adsorption of selected probe molecules, rather than to a systematic description of the adsorption of the very many probe molecules used over the years. Among the various physico-chemical aspects of aluminas, some were thought to be of particular interest: solid (bulk) and surface vibrations, the surface hydrated layer, surface basicity and surface acidity. Whenever possible, a comparison between spectroscopic and quantitative data has been proposed.